<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>雪碧图</title>
    <style>
        .demo{
            width: 40px;
            height: 46px;
            border:1px solid;
            background-image: ;
            background-repeat: no-repeat;
            background-position: 0px 0px;
        }
    </style>
</head>
<body>
    <pre>
        若网页图标数量过多，会影响网页的加载性能
        为了提高加载效率
    </pre>
    <div class="demo"></div>
</body>
</html>